// 基本类型的定义可以使用type
export type T1 = string;
// 默认推荐使用interface 进行对象类型定义
export interface T2 {
  x: number;
}
export type Foo = string | T2;

type T = string;
type Foo = string | {};

interface T {
  x: number;
}

// github
var foo = {};
interface A {}

interface A extends B {
  x: number;
}
type U = string;

type V = { x: number } | { y: string };

type Record<T, U> = {
  [K in T]: U;
};